Manny Pacquiao, unquestionably one of the best boxers of his generation, says his third meeting with Timothy Bradley Jr. on April 9 will be the final fight of his career. If that's the case, then it's time to assess Pacquiao's place in boxing history.

ESPN asked its panel of boxing experts to rank the top 25 pound-for-pound boxers of the past 25 years. The results will be unveiled over eight days on ESPN.com, Facebook (ESPN Boxing) and Twitter (@ESPNBoxing) and counted down from No. 25 to No. 1, which will be announced on the eve of Pacquiao-Bradley III. Fans can use the hashtag #P4Prank to join the discussion and follow along.

Is Pacquiao the No. 1 P4P boxer since 1991? Here are the ones ranked from No. 10 to No. 6:

Stats & Info: Lopez finished his career with a record of 25-0-1 (19 KOs) in world title fights, including 21 consecutive title defenses from 1990 to 1999.

ESPN's take: "Finito" was a marvel to behold, a fluid stylist who dispatched victims with elegant precision, considered by many to be the finest pure boxer of his era. Undefeated in 52 pro fights (38 KOs), the classy Mexican was limited only by his size and dearth of quality opposition. -- Nigel Collins

Stats & Info: Marquez was involved in the RING Magazine and BWAA 2009 Fight of the Year against Juan Diaz and 2012 Fight of the Year against Manny Pacquiao.

ESPN's take: The four-division titlist and Mexican legend built a reputation as one of the toughest and smartest boxers of his era. A master counterpuncher, his legacy will also be defined by longevity. Marquez rebuilt his body late in his career and had success at higher weight classes as a puncher. -- Brian Campbell

Stats & Info: Whitaker won the lineal and WBC welterweight champion from Buddy McGirt in 1993 and made eight title defenses from 1993 to 1997.

ESPN's take: The 1984 U.S. Olympic gold medalist was a defensive wizard who was nearly impossible to hit in his prime. Known for his quick jab and ring generalship, "Sweet Pea" won titles in four divisions and was inducted into the International Boxing Hall of Fame in 2007. -- Brian Campbell

Stats & Info: Holyfield is the only fighter in history to win a portion of the World Heavyweight Championship four times.

ESPN's take: I would have ranked him higher -- top 5 -- even though his greatest fights came in the 1990s. The toughest, most determined heavyweight I ever covered. Insisting the fight continue after Tyson bit off a chunk of his ear in their 1997 rematch has got to be ranked among the most courageous moments in boxing history. -- Wally Matthews

Stats & Info: De La Hoya won world titles in 6 different divisions, more than any American boxer in history.

ESPN's take: Often overlooked is that despite De La Hoya's movie star looks, suave style and mad skills, he was a genuine badass inside the ring. Never ducked anyone. Almost always went for the KO. All of which made him boxing's biggest crossover star and pay-per-view king of the 1990s and early 2000s. -- Nigel Collins